Tipless quartz lamp



Dec. 29, 1953 c. WIENER TIPLEss QUARTZ LAMP Filed Feb. 27, 1952 INVENTOR 'CA/P155 W/FIVEE ATTORNEY `ratenieri Dec. 29, 1953 perreo sbires PArsivr 2,664,517 TPIESS QUARTZ LAMP Charles Wiener, Bloomield, `N. J., assigner to Westinghouse Electric Corporation, East Pittsburgli, Pa., a corporation of Pennsylvania Application February V27,

1952, ScrialNe. 273,745

3 Claims. (Cl. 313-213) sThis inrention relates to electric discharge devices incre particularly, to mercury vapor lamps employed :for photocheinical processes.

he conventional mercury vapor lamp einploy'ed for photocheinieal processes comprises a long tubular intermediate-wattage source or" visible and. near ultra-violet light. This lamp coinn prises a 'high-silica glass envelope having thorium non-activateci electrodes sealed in each end. Due to its low internal operating vapor pressure and resultant ability to restart instantly after momentary interruptions, its principal field oi application is as a iight source for blueprinting niachines as a tool for effecting pliotochernical processes.

@ne of the chier" drawbacks of the conventional lamp is the exhaust tip on the body or" the envelope which casts a shadow and interrupts the photoprinting' and photochemical use of the lamp.

A further cirawbaek to the projecting @Xhust tip is that it has a relatively large area and naturally operates at a lower temperature because the loading per unit area is less. Drafts from the blue'orinting machine further cool the tip and cause the mercury to migrate thereto and condense until equilibrium oi condensation and evaporation is reached. The pressure at which a mercury vapor lamp operates is of course eietermined by the coolest portion of the lainp envelope.

To eliminate the objectionable exhaust tip on phe'tochernical mercury vapor lamps, a single bore enel portion which simultaneously acts as a means of evacuating 'the lamp and contains the molybdenum ribbon portion of the electrode leading-in conductor therein is sealed to one end of the lamp. However, during the baking operation on exhaust the deleterious gases released from the lamp envelope and pumped from the bulb interior through the single bore tubing contaminate the molybdenum ribbon and deposit a iim thereon. Later when the single bore tubing is collapsed anzi the ribbon embedded in the vitreous mass, this lin on the molybdenum ribbon prevents a tight bond between it and Jthe glass.

Hence, it has been found advantageous according to my invention to employ on one end of the lamp envelope a double bore of 9% silica (glass) such as sold by Corning Glass Works under the trade-mark (Vycor or quartz end portion which contains a molybdenum ribbon in preferably sealed between the wall of the bore and the partition adjacent the junction of the end portion and the lamp envelope, thereby preventing passage of any deleterious gases along the ribbon during the the exhaust position, ribbon sealing machine to c y both simultaneously and to eliminate any cavities wherein mercury vapor might condense. ln the lamp of my invention there is no exhaust tip proiecting laterally from the bocy the lamp envelope which might interfere with photoprinting or photoohernical oper In its general aspect, the object of overwritingthA vanta-aes of prior art merci v` por lamps eniployed forphotocheniical proce ses.

A specific object of my invention is 'a mercury vapor lamp for photo g ervice which eliminates any objectionab e aciow produced by projecticn from the envoi-o e body.

An aditional specie o ject is a tipless niercury vapor lamp for photorinting and photochemical service which eliminates any objectionable cavities in the envelope body wherein inercury might condense e' rietrir. entaliy afi-ect the lamp characteristics l.- operation.

A further object is oless ine'cury vapor lamp for photoprinting and photocheinical service wherein the inolybclenrAA 1 o of the electroaie leading-in conductor is nu ntaminateol during the baking operation on exhaust a vacuumtight seal is procluced.

An additional object is a ti :ess mercury vapor lamp for pliotoprinting ano iotochernical service having at least one loable bore end portion aiiiXed to the lamp envelope; one bore for sealing ori' the molybdenum efectrooe ribbon ano'. the other Vbore for an exhaust` ulation.

Other objects ana advantages oi the invention will appear to those si he art to which it appertains as the desclotion proceeds.

Referring to the accom-'1an lng drawing, in which like numerals reference indicate similar parts throughout the several views:

Fig. l is a side elevational view of a mercury vapor larnp for photo-chemical service and emboclyinfg,` my invention.

Fig. V2 is a sectional view of partitioned t nip of Fig. i, showing an electrode assembly in position for sealing.

Fig. 3 is a horizontal see-tici III`III of Fig. 2, in the fiirec Fig. 4 is a view sini a. 0. 2, but showing the sealing of the l portion of the molybdenum ribbon between the outer wall or" one bore andthe partition of the end portion at the junotion of the end portion and the envelope.

Fig. 5 is a horizontal sectional view on the l view on the line of the arrows.

line V-V oi' Fig. e, in the direction of the arrows.

Fig. o is a view similar to Figs. 2 and 4, but showing the use oi one bore as an exhaust tubulation on exhaust.

Fig. 'l is a view similar to Fig. 6, but showing the tipping ofi operation on exhaust.

Fig. S is a view similar to Fig. '1, but showing the collapsing of the exhaust tubulation bore and molybdenum ribbon bore of the end portion to seal said ribbon therebetween.

Referring to the drawing, larly to Fig. 1, a mercury vapor lamp for photoprinting and photochemical service is designated by the reference numeral iii. Although a mercury vapor lamp for photochemical service is shown in the present embodiment, it wiil be understood that the present invention is not restricted to use therewith. This lamp i comprises a tubular envelope i2, of high melting point vitreous material, having an elongated end portion iii, made from a double bore tube and an end portion i0, or" smaller diameter and like vitreous material made from a single bore tube and to which are respectively sealed electrode assemblies it and 2t.

As shown in Figures 2, 4, 6, 7, and 8, each of the electi'ode assemblies i8 and 20 desirably comprises a thorium electrode 22 mounted on one end of a short rod 2d of refractory material, such as tungsten or the like, as part o a leading-in conductor 20. The other end oi the rod 24 is welded to a strip or ribbon 2% of tantaium or molybdenum, about .0006" in thickness. A loop 2l of tantaium or molybdenum about .004 in thickness is secured as by welding to the opposite end cf the ribbon 25. After aiiixing the loop 2l to the ribbon 2%, the loop is cut so as to provide a V-shaped end portion having a spring tension capable oi securing the elctrode assemblies 2?. within the end portions i4, as hereinafter explained. i'he end portion id has a molybdenum ribbon sealing more 2e and an exhaust tubulation bore iis separated by a partition 3S.V

According to my invention, the electrode assembly is first positioned within the end portion it and sealed therein in the desired position. The other electrode assembly I8 is positioned by means of the V-shaped end portion 2l' within the molybdenum ribbon bore 28 o the double bore end portion iii, as shown in Figures 2 and 3. The lower end of portion Id at envelope i2 is heated by means, such as the fires 32 (Fig. 3), until the lower portion of the outer wall oi the bore 23 collapses upon the partition is@ and seals the lower portion of the ribbon 2S and the rod 2s therebetween. In this way the molybdenum ribbon 2S is sealed off from any contamination by deleterious exhaust gases.

ihe lamp i0 is then sealed to an exhaust manifold, by means ci end portion iii, and exhausted thru the bore 29, as shown in Fig. 6. This exhaust may comprise a suitable bake, an inert gas ush, final evacuation, a final fill with an inert gas such as argon, mercury fill, and tip-oi by a suitable torch sii as shown in Fig. 7.

After tip-ofi, the lamp I0 is then secured in a ribbon sealing machine and rotated between stationary sealing lires 36, as shown in Fig. 8, to heat the end portion iii substantially along its entire length and to cause the collapse of the outer wall portions upon the partition 30, thereby completely embedding the ribbon 26 in a vitreous mass and eliminating any objectionable and more particucavity in the end portion lli wherein mercury might condense during operation of the lamp l0. After the sealing operation, the end portions Hl and i0 are cut ofi by suitable means, such as a grinding wheel, to expose the outer ends of the V-shaped end portions 2l and thereby provide suitable external connections for operation of the lamp.

Thus it will be seen from the foregoing description that my invention has provided a tipless mercury Vapor lamp it for photoprinting and photochemical service, which does not cast an?,7 objectional shadows during photoprinting use, and which eliminates any projecting cavity wherein mercury might condense and vary the operating characteristics of the lamp. My lamp i0 employs at least one double bore partitioned end portion id having a molybdenum ribbon bore 28, wherein the molybdenum ribbon of the electrode asse bly i3 may be preliminarily sealed prior to the exhaust operation, and an exhaust tubulation bore 2S. Use of this double bore end portion ifi prevents the oxidation and contamination or the molybdenum electrode ribbon 26 during the exhaust operation and permits an improved hermetic seal between the ribbon 20 and the walls oi the double bore end portion lli.

Although an embodiment o my invention has been disclosed, it will be understod that modifications may be made.

I claim:

l. A tipless mercury vapor lamp for photoprinting and photochemical service comprising a vitreous envelope, provided with elongated end portions, an ionizable medium for supporting a discharge, oppositely disposed electrodes in said envelope between which a discharge occurs, leading in conductors for said electrodes, at least one oi which has a refractory metal ribbon embedded in a fused mass of vitreous material produced from a double-bore tube.

2. A tipless mercury vapor lamp for photoprinting and photochemical service comprising a vitreous envelope provided with elongated end portions, an icnizable medium for supporting a discharge, oppositely disposed thorium electrodes in said envelope between which a discharge occurs, leading-in conductors for said electrodes, at least one or which comprises a refractory metal rod, a molybdenum ribbon on said rod and a tantaium V-shaped end portion on said ribbon, said ribbon being embedded in a fused mass of vitreous material produced from a double-bore tube.

3. A mercury vapor lamp in condition for exhaust comprising a vitreous envelope provided with elongated end portions, at least one oi which is a double bore tube; oppositely disposed electrodes in said envelope, and leading-in conductors for said electrodes, at least one of which comprises a refractory metal ribbon sealed to one bore of the double bore tube, leaving the other bore for evacuating the envelope.

CHARLES WENER.

References Cited in the file O this patent UNITED STATES PATENTS 

